Apparatus and method for integrated access and backhaul in wireless communication system

ABSTRACT

A method of operating a node, for inter-node discovery, in a telecommunication network, the node being configured for Integrated Access and Backhaul (IAB) is provided. The method includes the steps of defining a Synchronization Signal Block (SSB) Transmission Configuration (STC) comprising information elements related to one or more of numerology, periodicity, offset, duration, SSB index, or location in the frequency domain; and transmitting, by the node, an SSB or SSB burst set according to the information elements in the STC.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 16/830,664, filed on Mar. 26, 2020, which has issued as U.S. Pat.No. 11,368,902 on Jun. 21, 2022, which application is based on andclaims priority under 35 U.S.C. § 119(a) of a United Kingdom patentapplication number 1904456.9, filed on Mar. 29, 2019, in the UnitedKingdom Intellectual Property Office, the disclosure of which isincorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to improvements to the operation of atelecommunication network by means of enhanced definition and operationof Synchronization Signal Block (SSB) Transmission Configuration (STC)and SSB Measurement Timing Configuration (SMTC) in an Integrated Accessand Backhaul (IAB) arrangement. More particularly, the disclosurerelates to Fifth Generation (5G) or New Radio (NR) systems but may applyin other systems also.

2. Description of Related Art

IAB refers to a configuration whereby air interface (i.e. access)channels are utilized for backhaul links. This arrangement raisescertain issues in network configuration and operation.

It is an aim of embodiments of the disclosure to address problems andshortcomings in the prior art, whether mentioned herein or not.

In the prior art standardization process, it has been agreed that SSBtransmission and measurement for inter-node discovery in IAB isconfigured in a centralized way by the Central Unit (CU) andconfiguration details are to be decided later.

It is an aim of embodiments of the disclosure to address issues with theprior art, whether mentioned herein or not.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providean apparatus and method as set forth in the appended claims.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

In accordance with aspect of the disclosure, a method of operating anode, for inter-node discovery, in a telecommunication network, the nodebeing configured for Integrated Access and Backhaul, IAB, comprising thesteps of defining a Synchronization Signal Block, SSB, TransmissionConfiguration, STC, comprising information elements related to one ormore of numerology, periodicity, offset, duration, SSB index andlocation in the frequency domain, the node transmitting an SSB or SSBburst set according to the information elements in the STC is provided.

A plurality of STCs are defined, relating to at least one of InitialAccess (IAS), and Inter-IAB node discovery (IND).

For the IND case, a plurality of STCs may be defined up to a maximumvalue K_(IND), which is determined by one or more of hop order, maximumnumber of neighboring IAB nodes, or maximum number of (SSB) TimingConfigurations (SMTCs) per IAB node.

STCs of different IAB nodes may be configured to be either adjacent orsubstantially adjacent to each other within a defined time period, ornon-adjacent to each other within a defined time period.

There may be further provided an operation of defining at least one SSBMeasurement Timing Configuration (SMTC) per IAB node, such that the atleast one SMTC configuration is co-ordinated with the respective STCconfiguration.

A pci-list may be configured for each at least one SMTC, detailing whichneighboring nodes are to be measured.

The duration of each SMTC may be defined such that multiple neighboringnodes are measured within one SMTC duration.

The duration may be defined such that it collides with its own STCconfiguration and the STC configuration overrides the SMTCconfiguration.

STC configuration may be coordinated across different IAB nodes. Thisallows the SMTC configuration complexity to be reduced.

The SMTC configuration may depend on RRC state or DRX state.

In accordance with another aspect of the disclosure, apparatus arrangedto perform the method of the first aspect is provided.

Embodiments of the disclosure provide configuration details for STC andSMTC for inter-node discovery and measurement in IAB networks subject tohalf-duplex constraint.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIGS. 1A and 1B illustrate adjacent and non-adjacent SSB/SSB Burst setaccording to various embodiments of the disclosure;

FIG. 2 illustrates an arrangement of STC and corresponding SMTC formultiple adjacent STC according to an embodiment of the disclosure;

FIG. 3 illustrates an arrangement of STC and corresponding SMTC formultiple non-adjacent STC according to an embodiment of the disclosure;

FIG. 4 illustrates an arrangement of STC and corresponding SMTC fordifferent STC periodicities according to an embodiment of thedisclosure; and

FIG. 5 illustrates an arrangement of SMTC for equivalent periodic STCaccording to an embodiment of the disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding, but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purposes only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Embodiments of the present disclosure provide STCs to address theaforementioned issues in the prior art.

An STC comprises a plurality of Information Elements (IEs). For eachSTC, one or more of the following IEs may be configured:

-   -   Numerology: SSB numerology including SCS and CP should be        indicated in STC;    -   Periodicity: periodicity of SSB transmission and should be in        the range of {5, 10, 20, 40, 80, 160} ms or extended up to the        range 320 and/or 640 and/or 1280 ms. The reason for periodicity        extension is because at least for inter-node SSB transmission,        longer periodicity can be assumed due to the fact that the IAB        nodes are static or with extremely low mobility so that        frequency transmission/measurement is not necessary;    -   Offset: this indicates the starting point of one SSB        transmission periodicity in terms of slot/subframe/SFN. The        value range of offset is from 0 to TP-1, where TP is the        configured periodicity;    -   Duration: this indicates how long the configured SSB        transmission will last;    -   SSB index: multiple SSBs can be transmitted in one SSB burst set        and SSB index indicates which SSBs will be actually transmitted;        and

Location in the frequency domain: STC can either be located on theraster of initial access STC but Time Division Multiplexed (TDMed) withinitial access STC or off the raster. In the latter case, the absolutelocation in the frequency domain of STC should be configured.

STC is not only configured for inter-node discovery but also for initialaccess of IAB nodes and access UEs. It has been agreed that these twotypes of SSBs should be at least TDMed. Therefore, at least 2 groups ofSTC should be configured as below:

Initial access STC (IAS) group: configured for initial access of accessUEs and IAB MTs; and

Inter-IAB node discovery (IND) group: configured for inter-nodediscovery purpose only.

At least one STC should be configured for IAS group and the maximumnumber of STCs can be defined in the Base Station (gNB) implementation.The configuration information can either be broadcast in systeminformation or configured via F1AP interface.

For the IND group, at least 1 STC should be configured. However,configuring too many STC in an IND group will introduce high signalingoverhead and a maximum value K_(IND) may be defined. K_(IND) can bedetermined by hop order and/or maximum number of neighboring IAB nodesand/or maximum number of SMTC per IAB node.

Single STC: only one STC is configured per IAB node for the IND group;

Hop order: the hop order is not expected to be larger than 4 so in thiscase, KIND can be up to 4;

Maximum number of neighboring IAB nodes: one IAB node is expected tohear up to two tier neighboring IAB nodes, i.e., 18 IAB nodesconsidering hexagon deployment, so in this case, KIND can be up to 18;

Maximum number of SMTC per IAB node: if KSMTC SMTC and KIND STC areconfigured per IAB node, inter-node discovery of up to

$\begin{pmatrix}{K_{SMTC} + K_{STC}} \\K_{STC}\end{pmatrix}$neighbouring IAB nodes can be supported. For example, if KSMTC=3, KINDcan be chosen as 3 to support up to 20 neighboring IAB nodes discovery,i.e., at least two tiers.

Within the IAS group, the same or different numerology, periodicity,offset, duration and SSB index can be configured for each STC per IABnode deployed in different raster points or between different IAB nodes.For the IND group, the same principle may be employed because adifferent STC is supposed to be measured by different IAB nodes in a TDMmanner, so at least different offset values should be configured foreach STC per IAB node.

Therefore, a basic solution is to allow independent configurations foreach STC in terms of numerology, periodicity, offset, duration and SSBindex. However, this will introduce a high signaling overhead,especially when multiple STCs need to be configured per IAB node. One ormore of the following arrangements may be considered for signalingoverhead reduction.

For numerology, and/or periodicity and/or duration and/or SSB index,multiple STCs can be configured with the same value to reduce signalingoverhead, i.e., configuring numerology, and/or periodicity and/orduration and/or SSB index for one STC and all the other STCs is expectedto follow the same numerology, and/or periodicity and/or duration and/orSSB index.

Another option is to let the STC in IND group follow the numerology,periodicity, duration, and/or SSB index of the IAS group to furtherreduce signaling overhead. If numerology, periodicity, duration, and/orSSB index is configured for an STC, such a configuration can be applied;otherwise, an STC should follow the default configuration, e.g., IASgroup configuration or one specific STC of IND group.

FIGS. 1A and 1B illustrate adjacent and non-adjacent SSB/SSB Burst setaccording to various embodiments of the disclosure.

Referring to FIG. 1A, multiple STCs of different IAB nodes can beconfigured adjacent or at least close to each other within a certaintime window. Such a configuration has the benefit of simple SMTCconfiguration, especially when the same periodicity is configured tomultiple STCs of different IAB nodes. For example, a single SMTC can beconfigured to measure all SSBs in one occasion and therefore signalingoverhead can be potentially reduced. In addition, a single offset valuecan be configured for one IND group to reduce signaling overhead. Forexample, an offset value is configured to node 1, and so, for nodes 2and 3, the offset value can be implicitly derived. However, if differentperiodicity is configured for each STC, a single SMTC may not besufficient. Moreover, adjacent STC configurations may impose anadditional scheduling constraint by enforcing all the nodes transmittingSSB in a certain time window.

Referring to FIG. 1B, another option is to configure non-adjacent STC.Such a configuration provides a higher level of flexibility, imposesless of a scheduling constraint and can easily handle the case ofmultiple STCs of different nodes with different periodicities. However,the corresponding SMTC configuration is more complicated and requires ahigher signaling overhead.

When multiple STC are configured per IAB node, a simplification may beconsidered.

An IAB node may not need to monitor the link quality of the establishedlinks to its parent node(s) and child node(s) because such informationcan be derived from CSI measurement and reporting. In this sense, thetotal number of neighboring IAB nodes that an IAB MT needs to measure isreduced and less STC is needed.

It has been agreed that multiple SMTCs (at least 3) can be independentlyconfigured per IAB node, i.e., periodicity, offset and duration can beconfigured independently. A consideration here is how to match themeasurement occasions, i.e., SMTC, with transmission occasions, i.e.,STC, subject to the half-duplex constraint. Potential enhancements forSMTC are as follows:

PCI List: In the current NR specification, two SMTCs can be configuredper node, one for the serving node and another for neighboring nodes.For the second SMTC for neighboring nodes, an RRC parameter pci-list isconfigured so that a UE knows which node(s) are to be measured. In IABnetworks, the serving node is treated in the same way as neighboringnodes by the IAB MT so that there is not a dedicated SMTC for theserving node measurement anymore. In each SMTC, multiple neighboringnodes might need to be measured. In such a case, the RRC parameterpci-list should be configured independently for each SMTC.

SMTC Duration: In the current NR spec, the duration of one SMTC can beup to 5 ms. This duration can be extended especially for the adjacentSTC case as shown in FIG. 2 .

FIG. 2 illustrates an arrangement of STC and corresponding SMTC formultiple adjacent STC according to an embodiment of the disclosure.

Referring to FIG. 2 , a single SMTC can be configured for both node 1and 3. Since two SSBs/SSB burst sets need to be measured in this SMTC,its duration should be doubled. Considering the case with more IAB nodesto measure, SMTC duration should be extended M times, where M is in therange of 2 to 8. For node 2, there are two different options (op1 andop2).

For option 1, two short SMTCs are configured to measure node 1 and 3,respectively, subject to the half-duplex constraint. For option 2, asingle long SMTC is configured but once the SMTC collides with theSMTC's own STC configuration, the SMTC is overridden by the STC, i.e.,instead of measuring other nodes, node 2 transmits SSB in the slotmarked as X in the figure. The benefit of such a configuration is thatonly one SMTC needs to be configured and so the signaling overhead canbe reduced. When considering the case with more nodes involved, thesignaling overhead reduction is significant. Such an overriding rule canbe either implicitly or explicitly configured.

FIG. 3 illustrates an arrangement of STC and corresponding SMTC formultiple non-adjacent STC according to an embodiment of the disclosure.

Referring to FIG. 3 , for non-adjacent STCs, multiple SMTCs can beconfigured. As mentioned before, multiple STCs can be configured per IABnode and, as shown in FIG. 3 , each node is configured with two STCs andtwo SMTCs for measurement. The following configurations may be employed:

-   -   Node 1: node 1 transmits SSB in occasion 1 and 4 based on STC        and measures node 3 in occasion 2 and node 2 and 4 in occasion        3;    -   Node 2: node 2 can be configured with 2 SMTCs with normal        duration and measures node 1 and 4 in occasion 1 and node 3 in        occasion 2. Node 2 can also be configured with a single SMTC        with longer duration to measure all the other nodes. The latter        configuration has lower signaling overhead;    -   Node 3: for node 3, two SMTCs are configured. In occasion 1,        node 3 can measure node 1 and 4 and in occasion 3, node 3 can        measure node 2 and 4. In such a case, node 4 is measured twice.        However, if pci-list is configured (see previously), node 3 can        only measure node 2 in occasion 3 to reduce measurement        complexity. Another alternative is to split the measurement of        node 4 into two occasions, e.g., measure some beams from node 4        in occasion 1 and other beams from node 4 in occasion 2. This        can be achieved by configuring different SSB index for the two        STCs of node 4;    -   Node 4: node 4 is configured with a single SMTC and measures        node 1, 2 and 3 in occasion 4.

FIG. 4 illustrates an arrangement of STC and corresponding SMTC fordifferent STC periodicities according to an embodiment of thedisclosure.

Referring to FIG. 4 , such a configuration can also be extended to thecase where periodicities of different nodes are different. Theperiodicity of node 3 is a quarter of the periodicity of nodes 1 and 2.The following configurations may be considered:

Node 1:

-   -   Op1: a single SMTC with longer periodicity can be configured.        The benefit of such a configuration is that only one SMTC needs        to be configured so that the signaling overhead can be reduced.        However, it may measure nothing in some occasions and so impose        an unnecessary scheduling constraint;    -   Op2: multiple SMTCs are configured with different periodicities.    -   Node 2: same as node 1, two options can be considered;    -   Node 3: a single longer SMTC can be configured.

FIG. 5 illustrates an arrangement of SMTC for equivalent periodic STCaccording to an embodiment of the disclosure.

Referring to FIG. 5 , if STC can be coordinated across multiple nodes,the overall equivalent SSB/SSB burst set transmission can be periodic.The equivalent SSB Tx is uniformly distributed in a periodic manner, asshown.

In such a case, a single SMTC can be configured for each node to simplymeasure every SSB Tx occasion. When STC collides with SMTC, theaforementioned overriding rule can be applied.

For example, node 1 needs to transmit SSB in occasion 1 and 4 (markedwith X in the lower part of the figure) even though its SMTCconfiguration indicates to measure other nodes. One issue for suchconfiguration is the IAB MT does not know which neighboring IAB node(s)to measure in a certain occasion. One solution is to configure apci-list with all potential IAB nodes, let the IAB MT measure SSBs fromother IAB nodes blindly and identify each IAB node by exploring the ZCsequence correlation property.

Another solution is to configure multiple pci-lists so an IAB MT knowswhich IAB node(s) to measure in each occasion. For example, two pci-listare configured for node 1, one including node 3 and another includingnodes 2 and 4.

In the current NR specification, different numbers of SMTCs areconfigured for RRC-IDLE and RRC_Connected states. For RRC_IDLE state,only one SMTC is allowed but for RRC_Connected state, two SMTCs may beconfigured. However, in IAB networks, even in RRC_IDLE state, the IAB MTstill needs to monitor neighboring IAB nodes so more than one SMTCshould be configured in RRC_IDLE state.

In the current NR specification, SMTC is not defined for RRC_INACTIVEstate. However, for IAB MT, it may stay in RRC_INACTIVE state and ifthat happens, the number of SMTC windows should be defined. It caneither be fewer SMTC windows than the RRC_CONNECTED state (e.g., oneSMTC window to reduce signaling overhead), or multiple SMTC windows(e.g., the same number of SMTC windows as in RRC_CONNECTED state).

Moreover, RRC_IDLE and RRC_INACTIVE states may not be defined for IABMT. In such a case, long Discontinuous Reception (DRX) may be definedfor IAB MT which remains in RRC_ACTIVE state. A different number of SMTCwindows can be defined when IAB MT is active and sleeping following thesame principles mentioned above, e.g., same or fewer SMTC windows forsleeping compared to active.

In addition, the STC and SMTC configurations should take hop order intoaccount for the following reasons:

Avoiding Uplink (UL)/Downlink (DL) switching: there are two cases: 1) anIAB node, denoted as node A, can receive where its parent node and otherIAB node with the same hop order of its parent node transmit in slot n;and 2) IAB node A and other IAB nodes with the same hop order receive atthe same time in slot n. For case 1, STC can be configured for parentnode(s) of IAB node A and SMTC can be configured for IAB node A in thesame time slot n without need for UL/DL switching at either side.However, for case 2, if STC is configured for parent node(s) of IAB nodeA and SMTC is configured for IAB node A in the same time slot n, UL/DLswitching is needed due to half-duplex constraint. Two groups ofSTC/SMTC can be considered, where one group is for intra-layer andanother for inter-layer.

Taking hop order into account may potentially reduce the number oftransmission/measurement occasions, leading to lower signaling overheadand complexity and higher efficiency.

At least some of the example embodiments described herein may beconstructed, partially or wholly, using dedicated special-purposehardware. Terms such as ‘component’, ‘module’ or ‘unit’ used herein mayinclude, but are not limited to, a hardware device, such as circuitry inthe form of discrete or integrated components, a Field Programmable GateArray (FPGA) or Application Specific Integrated Circuit (ASIC), whichperforms certain tasks or provides the associated functionality. In someembodiments, the described elements may be configured to reside on atangible, persistent, addressable storage medium and may be configuredto execute on one or more processors. These functional elements may insome embodiments include, by way of example, components, such assoftware components, object-oriented software components, classcomponents and task components, processes, functions, attributes,procedures, subroutines, segments of program code, drivers, firmware,microcode, circuitry, data, databases, data structures, tables, arrays,and variables. Although the example embodiments have been described withreference to the components, modules and units discussed herein, suchfunctional elements may be combined into fewer elements or separatedinto additional elements. Various combinations of optional features havebeen described herein, and it will be appreciated that describedfeatures may be combined in any suitable combination. In particular, thefeatures of any one example embodiment may be combined with features ofany other embodiment, as appropriate, except where such combinations aremutually exclusive. Throughout this specification, the term “comprising”or “comprises” means including the component(s) specified but not to theexclusion of the presence of others.

Attention is directed to all papers and documents which are filedconcurrently with or previous to this specification in connection withthis application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings) may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The disclosure is not restricted to the details of the foregoingembodiment(s). The disclosure extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by an integrated access andbackhaul (IAB) node in a wireless communication system, the methodcomprising: receiving, from a base station, configuration informationincluding a synchronization signal (SS)/a physical broadcast channel(PBCH) block (SSB) measurement timing configuration (SMTC) for IAB nodediscovery, wherein the SMTC includes a cell list for the IAB nodediscovery; and performing a measurement of at least one SSB for the IABnode discovery based on the configuration information.
 2. The method ofclaim 1, wherein the SMTC includes information on a periodicity andinformation on an offset for the IAB node discovery.
 3. The method ofclaim 1, wherein the SMTC includes information on a duration for the IABnode discovery.
 4. The method of claim 1, further comprising: receiving,from the base station, an SSB transmission configuration (STC)comprising information related to one or more SSB indexes, a location ina frequency domain, a numerology, a periodicity, an offset, or aduration; and transmitting an SSB or SSB burst set according to theinformation in the STC, wherein a plurality of STCs are defined asrelating to at least one of initial access (IAS) or inter-IAB nodediscovery (IND).
 5. The method of claim 4, wherein, for the IND, theplurality of STCs are defined up to a maximum value K_(IND), which isdetermined by at least one of a hop order, a maximum number ofneighboring IAB nodes, or a maximum number of SMTCs per IAB node.
 6. Themethod of claim 4, wherein STCs of different IAB nodes are configured tobe either: adjacent or substantially adjacent to each other within adefined time period, or non-adjacent to each other within the definedtime period.
 7. The method of claim 4, wherein the STC is coordinatedacross different IAB nodes.
 8. The method of claim 1, wherein a durationof the SMTC is defined such that multiple neighboring nodes are measuredwithin one SMTC duration.
 9. The method of claim 8, wherein the durationis defined such that the duration collides with a SSB transmissionconfiguration (STC) and the STC overrides the SMTC.
 10. An integratedaccess and backhaul (IAB) node in wireless communication system, the IABnode comprising: a transceiver; and at least one processor operablycoupled to the transceiver, the at least one processor configured to:receive, from a base station, configuration information including asynchronization signal (SS)/a physical broadcast channel (PBCH) block(SSB) measurement timing configuration (SMTC) for IAB node discovery,wherein the SMTC includes a cell list for the IAB node discovery; andperform a measurement of at least one SSB for the IAB node discoverybased on the configuration information.
 11. The IAB node of claim 10,wherein SMTC includes information on a periodicity and information on anoffset for the IAB node discovery.
 12. The IAB node of claim 10, whereinSMTC includes information on a periodicity and information on an offsetfor the IAB node discovery.
 13. The IAB node of claim 10, wherein the atleast one processor is further configured to: receive, from the basestation, an SSB transmission configuration (STC) comprising informationrelated to one or more SSB indexes, a location in a frequency domain, anumerology, a periodicity, an offset, or a duration, and transmit an SSBor SSB burst set according to the information in the STC, and wherein aplurality of STCs are defined as relating to at least one of initialaccess (IAS) or inter-IAB node discovery (IND).
 14. The IAB node ofclaim 13, wherein, for the IND, the plurality of STCs are defined up toa maximum value K_(IND), which is determined by at least one of a hoporder, a maximum number of neighboring IAB nodes, or a maximum number ofSMTCs per IAB node.
 15. The IAB node of claim 13, wherein STCs ofdifferent IAB nodes are configured to be either: adjacent orsubstantially adjacent to each other within a defined time period, ornon-adjacent to each other within the defined time period.
 16. The IABnode of claim 13, wherein the STC is coordinated across different IABnodes.
 17. The IAB node of claim 10, wherein a duration of the SMTC isdefined such that multiple neighboring nodes are measured within oneSMTC duration.
 18. The IAB node of claim 17, wherein the duration isdefined such that the duration collides with a SSB transmissionconfiguration (STC) and the STC overrides the SMTC.